This present invention relates generally to a surgical instrument that can use ultrasound to influence and energize a liquid such as water to form the blade of a knife or scalpel with improved cutting abilities. More particularly the invention relates to an ultrasound liquid scalpel having improved properties for use during surgical operations involving cutting through skin tissues, organ tissues and other tissues.
Generally, a scalpel is a tool for cutting through skin and/or other soft tissues during surgeries. U.S. Pat. No. 2,650,426 to Montelius, U.S. Pat. No. 5,055,106 to Lundgren and U.S. Pat. No. 5,078,724 to Takase describe examples of scalpels known in the prior art. These surgical scalpels comprise basically a cutting edge, such as a blade attached to a handle. In addition to use in surgery scalpels generally, as well as the present invention in particular, may be used in a variety of cutting application in the arts, crafts and other precision cutting processes for cutting wood, paper, plastics, foams and other natural and man-made materials. The size and shape of the blade and handle vary depending on the particular application of use.
Due to problems associated with such surgical scalpels such as, but not limited to, the application of too much pressure on the cutting area, trauma, and scaring, ultrasonic scalpels using metal blades were developed. Ultrasonic scalpels are well known in the art and used widely for surgical operations. An ultrasonic scalpel can reduce bleeding and reduce the amount of pressure needed during cutting. As such, ultrasonic scalpels using metal blades may eliminate some of the trauma associated with pressure applied to the cut and with the surgery in general.
Using metal bladed ultrasonic scalpels can reduce the scarring and bleeding associated with surgical operations compared to ordinary scalpels lacking ultrasound energy. Examples of related devices are disclosed in U.S. Pat. No. 5,167,725 to Clark et al, and U.S. Pat. No. 6,514,267 to Jewett. The cauterization effect of ultrasound is also utilized in related devices such as U.S. Pat. No. 5,263,957 to Davison and U.S. Pat. No. 5,324,299 to Davison et al.
Despite their advantages, the prior art ultrasonic scalpels fail to effectively cut through skin and/or soft tissue without inflecting collateral damage on the skin and/or soft tissue being cut. The infliction of collateral damage occurs because most prior art ultrasonic scalpels are designed to be used with longitudinal motions which either result in excessive bleeding from the incision, require the application of excessive pressure on tissue, or are insufficient for cutting without damaging the surrounding skin and/or soft tissue. Such trauma to viable tissue can impede the healing potential. Necrosis (i.e., death of cells and living tissue) may also result from the trauma. Necrosis is caused by the continuous friction created from the blade's cutting edge and/or surface being in continuous contact with the skin and/or tissue as it is chit, leading to acoustic burns. Such continuous contact is the outcome of the blade's repeated longitudinal motion during cutting. The resulting damage to the surrounding skin and/or tissue is often irreversible.
Cutting devices using water as a blade material such as; U.S. Pat. No. 5,944,686 to Patterson et al., U.S. Pat. No. 6,511,493 to Moutafis et al and U.S. Pat. No. 7,122,017 to Moutafis et al provide a very highly pressurized stream of water that may be used for cutting tissue. As a result of the high discharge pressures, relatively large volumes of water are discharged from the cutting devices. To facilitate collecting this water, the devices generally have a return orifice opposite the supply orifice within a cavity, thereby confining the water cutting surface entirely within the cavity. Although this configuration is effective at returning the water for collection, it effectively shrouds the cutting blade making it very difficult to access on the body to be cut. Accessing body tissue often requires pressing the device into the surrounding tissue so that the water cutting surface may make contact with the tissue being cut. This pressure may be necessary to access the tissue, but may also result in extensive pain to the patient during the procedure, especially when cutting tissue in injured or sensitive areas of the patients body.
Cutting devices using water and ultrasound for debridement have been developed. Examples within the prior art include, U.S. Pat. No. 7,025,737 to Soring et al., U.S. Pat. No. 6,569,099 to Babaev and U.S. App. No. 20070287934 to Babaev. These devices may be used for debridement but do not disclose a scalpel using a liquid influenced by ultrasound energy to form a knife blade that is useable for routine surgical applications.